Manufacture of rubber



Patented Sept. 7, 1926. 4

UNITED STATES PATENT OFFICE.

CHAUNCEY C. LOOMIS, OE YONKERS, AND HORACE IE. 'STUMB, OF BROOKLYN, NEW YORK, ASSIGNORS, BY MESNE ASSIGNMENTS, TO THE HEVEA. CORPORATION, A

CORPORATION OF NEW YORK.

muracrunnor RUBBER.

Ito Drawing.

This invention relates in general to the manufacture of rubber and has for its object broadly the provision of a more direct and economical process than has hereto- 5 forebeen existent. I

A principalIobject.- of the invention is the provision of a process of making rubber article direct from the latex itselfand without the need of costly or complicated in machinery or apparatus. Prior to our invention it has been generally the custom in the rubber industry to form crude rubber by complete coagulation of latex where the rubber is grown "and after this rubber is re-. ceived in this 1 country to Work into the crude rubbe'rthe various compounding ingredients, as vulcanizing agents, fillers, pigments, accelerators, etc. This last has een a diflicult and costly operation and-one which this inventionv contemplates entirely orsubstantially entirely eliminating.

Another, important object of the invention is the provision of a process which will obviate the washing and milling of rubber,

result in the productionof a product of improved quality. a a A particular use of the invention is the manufacture, economically, of rubber sheeting, rubberized or frictioned cloth, belting and the like, of improved quality and consequently the provision of a process for accomplishing such result isa particular object of the invention. The invention, how- .ever, from certain aspects has very much wider, valuable application, beingca able, as will be presently manifest, of va uable use in the manufacture of rubber in any form and for any purpose.

In accordance with our present invention a natural latex (as rubber, gutta-percha,

balata and the like) is partially coagulated and in the partially coagulated conditionis formed or applied in the manner but very much more easily than the compounded rubber in the past and after application or forming the coagulation is com leted. We have dlscovered that undialyze latex. may be partiallycoagulated with the usual rub berdcoagulants, such as acetic acid, or formic aci the latex with a stabilizing agent, such as formaldehyde, tannic: acid, salts of the alkaand which on this and other accounts will v the use of crude-rub To do this it is necessary to first treat Application filed April 10; 1923. Serial No. 631,2D9. I

line earths; or salts of the heavy tri-valent metals. If the coagulant be then added in small increments there is a progressive change, from a milky conslstency to a plastic, non-elastic paste. In this condition the rubber is only partially'coagulated, since complete coagulation produces the wellvknown elastic, non-plastic properties of crude rubber.

The plastic, non-elastic paste of semi- .coagulated rubber cannotbe produced with aceticorformic acids without the use of a stablhzer. The exact action of the stabilizer has not been ascertained, but it is believed' that it jlls the protein in the latex.

A paste of semi-coagulated rubber can also be produced bytreating the latex with salts of the alkaline earths or of the heavy tri valentf metals without the addition of one of the usual coagulants. In this case the salts referred to'appear to act bothas stabilizer and coagulant.

' In either of the. above cases, if sufiicient coagulant be addd'the latex will be completely coagulated into the usual crude rubber.

The present invention contemplates th addition'of coagulant until alastic paste ofdeslred consistency-is reache ,which may be formed into substantially the form des1r ed in the finished rubber. For example, this paste may be spread out in the form of a sheet of desiredthickness. If thereafter.

the moisture is extracted, preferably by pressure although it may be otherwise extracted, the coagulation automatically continues to produce the. irreversible rubber itself. If

desired, protective colloids as gelatine, casein, agar agar, etc., may be incorporated in'the latex to insure against premature conversion of the material into rubber. This paste may conveniently be applied by spreading it upon cloth or other fibrous material to produce rubberized or frictioned cloth or upon belting to Thusconstructedt e material when finished duced in the manufacture of rubberized terial is frictionedbymhegwy ht 1' in a nap ,ar

provide' friction surface." 100. gives a higher friction test than that pro-.-

vent. If it. is desired to vulcanize the material, as perhaps will usually bethe case, the compounding ingredients may. be incorporated in it before the coagulation, and exstantially the shapeperiment' has demonstratedthat thus incorporated, remarkably easy uniformity of dis-' trlbution of the ingredients is obtained in the finished product.

This paste may also, of course, be spread out upon a wire or reticulate surtace,pressed to extract the moisture,.and the resulting sheet vulcanized to make a-high grade but:

cheaply produced rubber sheeting. Itis preferred that the moisture be extracted by pressing since in this event the soluble impurities are removed and if this is un-importan-t, evaporation of the moisture accomplishes otherwise the same result; From certain aspects'of. the invention it is therefore unimportant whether "the moisture 'be extracted by pressure or-evaporation and from certain aspects decidedly important.

1. The process, which comprises partially coagulating a natural latex to produce a plastic paste, formin the same ninto subrubber article, and converting-the formed material mto rubber.. v

p 2. The rocess, which COD1P I1SS mixmg compounding materials with .latex, partiallycoagulating the same to produce a plastic paste; forming itinto substantially the shape of the rubber roduct desired, and converti g the'formc material'into rubber;

diasired in the finished- "3. The process, which comprises mixing I compounding materials with latex, partially coagulating the same to produce a plastic paste, forming it into substantially the shape of the rubber product desired, converting .the formed material into rubber, and vulcanizing. Y o 4. The process, which comprises partially coagulating a natural latexinto a plastic material, arranging said material in sheet form, and, converting said sheet material into rubber.

5. The process, which'comprises partially coagulating a natural latex to plastic form,

spreading the same upon a fibrous sheet, and. I

extracting the moisture to convert the material into rubber.

6. The process, which comprises partially 8., The process, which comprises, adding a protective colloid to a natural latex and ing the zlatexxto apa'ste.

- CHAUNCEY O. LOOMIS.

HORACE. E.- STUMP.

60 thickening the same by partially coagulat- I 

